Maintaining weight while following a low FODMAP diet

Maintaining weight while following a low FODMAP diet (4).png

Dakota Rhys-Jones - Research Dietitian, 29 March 2021

We often get asked here at Monash FODMAP about how best to maintain energy levels and avoid weight loss while following a low FODMAP diet. First of all, we want to flag that the low FODMAP diet is not a diet that should be followed for weight loss purposes, and is instead a diet followed by those who have IBS that has been diagnosed by an appropriate health professional.

Restrictive diets and unintentional weight loss:

Diets that reduce or restrict different food groups (i.e. vegan/vegetarian), without sensible planning, can mean different nutrients are at risk of not being met. Sometimes individuals following restrictive diets can lose weight without meaning to, working with a trained dietitian is particularly important if this is the case. They will help to identify key nutrients that are at risk due to reducing or excluding those foods, and how best the individual can ensure nutritional requirements are met while keeping to the diet. 

When it comes to the low FODMAP diet, we know that the first step can be challenging, and we know that those who have support from a dietitian have increased success of the diet compared to those who do not. Unlike other restrictive diets that may be more permanent, the stricter low FODMAP phase lasts only 2-6 weeks and is not recommended long-term. After 2-6 weeks, as the individual learns more about their sensitivities, there should be more flexibility in the diet.

Tips to avoid weight loss:

Meal times

Rather than focusing on 3 main meals a day, try 6 smaller meals, spaced out throughout the day. Sometimes larger meals can become overwhelming and fill us up too quickly.

Foods containing energy

Carbohydrates, fats and proteins all provide us with energy. We generally rely on carbohydrates and fats as the main source of energy, and if our body doesn’t get enough energy from these, we use protein. See the below list for some low FODMAP foods that help to provide energy in the diet:

  • Carbs:  potatoes, rice, popcorn, oats, quinoa, maple syrup, strawberry jam, spelt sourdough/gluten free bread
  • Fats: nuts (almonds/macadamias), nut spreads, small serves of avocado, margarine, seeds, olive oil, oily fish e.g. salmon, tuna. Note: fats are naturally low in FODMAPs, however some people find excess dietary fat can exacerbate their symptoms - spread fat intake throughout the course of the day. 

Add protein sources at meal times and fill up on these first

The main function of protein is muscle repair and regeneration and without enough protein in the diet, we can start to break down muscle mass. Naturally, animal sources of protein will contain no FODMAPs, while vegetarian sources can introduce FODMAPs (check our app for serve size). Try to include a source of these low FODMAP proteins at meal times:

  • Animal sources: Eggs, chicken, lamb, beef, fish, pork, turkey. Check that no added FODMAPs are introduced such as onion/garlic sauces used as flavourings.
  • Vegetarian sources: Firm tofu, tempeh, peanut butter, dairy products (low lactose if required), soy milk (made from soy protein), nuts (walnuts, peanuts, macadamia, brazil nuts, pine nuts)


Dairy is a great source of energy, protein, as well as calcium in the diet. While some people with IBS may have to follow a lactose-free diet, this does not mean dairy free! Aim for full-fat dairy products while trying to increase energy. For those who can’t tolerate dairy, soy-based beverages (made from soy protein) are an appropriate alternative compared to other plant-based milks.

Food fortification – make every mouthful count

Fortifying meals is a way of adding extra energy and/or protein in your diet without having to increase the amount you actually eat. Foods like fruits and vegetables, while extremely nutritious, are lower in energy and protein compared to other foods. These foods can easily be fortified to ensure you eat enough energy. Below are some food fortification tips while following a low FODMAP diet:

  • Low FODMAP fruit salad: add lactose-free yoghurt and maple syrup
  • Soups: add in grated cheese
  • Sandwiches: include a source of protein (peanut butter/cheese/eggs/ham) and add mayonnaise and/or butter

Nourishing drinks

Nourishing drinks are sources of energy and protein, and are useful when we don’t feel like eating. Filling up on other drinks like tea, water and coffee (black) do not provide us with nutrition and can fill us up before we actually get to eat. Fruit smoothies, like our summer berry smoothie, made with low FODMAP fruit, milk (soy-based or lactose-free), and yoghurt (lactose-free) are a great nourishing drink.

Meal plan:

Below are some suggested meal options, see our website at for many more delicious low FODMAP recipes.

If you are experiencing unintentional weight loss while following a low FODMAP diet, see your GP or a Monash FODMAP trained dietitian.

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